Psychology News & Resources

Northwestern University researchers have provided new biological evidence suggesting that the brain works differently when memorizing the face of a person from one’s own race than when memorizing a face from another race.

Their study — which used EEG recordings to measure brain activity — sheds light on a well-documented phenomenon known as the “other-race effect.” One of the most replicated psychology findings, the other-race effect finds that people are less likely to remember a face from a racial group different from their own.

“The ability to accurately remember faces is an important social skill with potentially serious consequences,” says doctoral student Lucas, lead author of the recently published study in Frontiers in Human Neuroscience. “It’s merely embarrassing to forget your spouse’s boss, but when an eyewitness incorrectly remembers a face, the consequence can be a wrongful criminal conviction,” she adds.

The Northwestern team found that brain activity increases in the very first 200 to 250 milliseconds upon seeing both same-race and other-race faces. To their surprise, however, they found that the amplitude of that increased brain activity only predicts whether an other-race face (not a same-race face) is later remembered.

“There appears to be a critical phase shortly after an other-race face appears that determines whether or not that face will be remembered or forgotten,” Lucas says. “In other words, the process of laying down a memory begins almost immediately after one first sees the face.”

Previous research has associated this very early phase — what is known as the N200 brain potential — with the perceptual process of individuation. That process involves identifying personally unique facial features such as the shape of the eyes and nose and the spatial configuration of various facial features.

When the researchers asked the 18 white study participants to view same-race faces and to commit them to memory, the individuation process indexed by N200 appeared “almost automatic — so robust and reliable that it actually was irrelevant as to whether a face was remembered or not,” says Lucas.

Minutes later, the participants were given a recognition test that included new faces along with some that were previously viewed. The researchers analyzed brain activity during initial face viewing as a function of whether or not each face was ultimately remembered or forgotten on the recognition test.

The N200 waves were large for all same-race faces, regardless of whether or not they later were successfully remembered. In contrast, N200 waves were larger for other-race faces that were remembered than for other-race faces that were forgotten.

Of course, not all same-race faces were successfully recognized, the researchers say. Accordingly, their study also identified brain activity that predicted whether or not a same-race face would be remembered. A specific brain wave starting at about 300 milliseconds and lasting for several hundred milliseconds was associated with what the psychologists call “elaborative encoding.”

In contrast to individuation (which involves rapidly identifying unique physical attributes from faces), elaborative encoding is a more deliberate process of inferring attributes. For example, you might note that a face reminds you of someone you know, that its expression appears friendly or shy, or it looks like the face of a scientist or police officer.

Making these types of social inferences increases the likelihood that a face will be remembered.

“However, this strategy only works if the process of individuation also occurred successfully — that is, if the physical attributes unique to a particular face already have been committed to memory,” Lucas says. “And our study found that individuation is not always engaged with other-race faces.”

Why is individuation so fragile for other-race faces? One possibility, the researchers say, is that many people simply have less practice seeing and remembering other-race faces.

“People tend to have more frequent and extensive interactions with same-race than with other-race individuals, particularly racial majority members,” Lucas says. As a result, their brains may be less adept at finding the facial information that distinguishes other-race faces from one another compared to distinguishing among faces of their own racial group.

Another possible explanation involves “social categorization,” or the tendency to group others into social categories by race. “Prior research has found that when we label and group others according to race we end up focusing more on attributes that group members tend to have in common — such as skin color — and less on attributes that individuate one group member from others,” Lucas says.

As a result, smaller N200 brain potentials for other-race faces — particularly those that were not remembered later — could indicate that race-specifying features of these faces were given more attention.

The Northwestern researchers expect future research to build on their findings in the continuing effort to better understand the other-race effect. “That research also will need to focus more on face recognition in minorities, given that the bulk of research to date has examined majority-white populations,” Lucas says.

Medication and behavioural interventions help children with attention deficit hyperactivity disorder (ADHD) better maintain attention and self-control by normalising activity in the same brain systems, according to research funded by the Wellcome Trust.

In a study published today in the journal ‘Biological Psychiatry’, researchers from the University of Nottingham show that medication has the most significant effect on brain function in children with ADHD, but this effect can be boosted by complementary use of rewards and incentives, which appear to mimic the effects of medication on brain systems.

ADHD is the most common mental health disorder in childhood, affecting around one in 20 children in the UK. Children with ADHD are excessively restless, impulsive and distractible, and experience difficulties at home and in school. Although no cure exists for the condition, symptoms can be reduced by a combination of medication and behaviour therapy.

Methylphenidate, a drug commonly used to treat ADHD, is believed to increase levels of dopamine in the brain. Dopamine is a chemical messenger associated with attention, learning and the brain’s reward and pleasure systems. This increase amplifies certain brain signals and can be measured using an electroencephalogram (EEG). Until now it has been unclear how rewards and incentives affect the brain, either with or without the additional use of medication.

To answer these questions, researchers at Nottingham’s Motivation, Inhibition and Development in ADHD Study (MIDAS) used EEG to measure brain activity while children played a simple game. They compared two particular markers of brain activity that relate to attention and impulsivity, and looked at how these were affected by medication and motivational incentives.

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The team worked with two groups of children aged nine to 15: one group of 28 children with ADHD and a control group of 28. The children played a computer game in which green aliens were randomly interspersed with less frequent black aliens, each appearing for a short interval. Their task was to ‘catch’ as many green aliens as possible, while avoiding catching black aliens. For each slow or missed response, they would lose one point; they would gain one point for each timely response.

In a test designed to study the effect of incentives, the reward for avoiding catching the black alien was increased to five points; a follow-up test replaced this reward with a five-point penalty for catching the wrong alien.

The researchers found that when given their usual dose of methylphenidate, children with ADHD performed significantly better at the tasks than when given no medication, with better attention and reduced impulsivity. Their brain activity appeared to normalise, becoming similar to that of the control group.

Similarly, motivational incentives also helped to normalise brain activity on the two EEG markers and improved attention and reduced impulsivity, though its effect was much smaller than that of medication.

“When the children were given rewards or penalties, their attention and self-control was much improved,” says Dr Maddie Groom, first author of the study. “We suspect that both medication and motivational incentives work by making a task more appealing, capturing the child’s attention and engaging his or her brain response control systems.”

Professor Chris Hollis, who led the study, believes the findings may help to reconcile the often-polarised debate between those who advocate either medication on the one hand, or psychological/behavioural therapy on the other.

“Although medication and behaviour therapy appear to be two very different approaches of treating ADHD, our study suggests that both types of intervention may have much in common in terms of their affect on the brain,” he says. “Both help normalise similar components of brain function and improve performance. What’s more, their effect

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is additive, meaning they can be more effective when used together.”

The researchers believe that the results lend support from neuroscience to current treatment guidelines

for ADHD as set out by the National Institute for Health and Clinical Excellence (NICE). These recommend that behavioural interventions, which have a smaller effect size, are appropriate for moderate ADHD, while medication, with its larger effect size, is added for severe ADHD.

Although the findings suggest that a combination of incentives and medication might work most effectively, and potentially enable children to take lower doses of medication, Professor Hollis believes more work is needed before the results can be applied to everyday clinical practice or classroom situations.

“The incentives and rewards in our study were immediate and consistent, but we know that children with ADHD respond disproportionately less well to delayed rewards,” he says. “This could mean that in the ‘real world’ of the classroom or home, the neural effects of behavioural approaches using reinforcement and rewards may be less effective.”

About Peter

Peter Brown BHMS (Hons) MPsychClin MAPS

I’m a Clinical Psychologist and have a private practice and consultancy in Brisbane Australia. I have 24 years experience in child, adult and family clinical psychology. I have a wonderful wife and three kids.

I like researching issues of the brain & mind, reading and seeking out new books and resources for myself and my clients. I thought that others might be interested in some of what I have found also, hence this blog…